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No, they are not just a matter of opinion (although there is some small subjective element to it). If our eyes somehow detected the exact wavelength of light d

No, they are not just a matter of opinion (although there is some small subjective element to it). If our eyes somehow detected the exact wavelength of light directly then, yes, we would perceive a continuum of colours and it would be totally arbitrary how you divide it up. But we don't. As the article says, we have a discrete set of cone types that divide our perception of colours up into clusters (albeit overlapping and fuzzy). For that reason, for most people with normal vision, a rainbow appears to have 6 main colours.

itishappy 2y ago
We have a discrete set of cones but they have continuous outputs so the space is indeed a continuum. The 6 colors of the rainbow are arbitrary and cultural (I've always learned there are 7). There's no physiological reason we say orange is a color but dark orange isn't. We perceive more than 7 colors.
- adastra22 2y ago
  The rainbow as perceived by most humans has six distinct color peaks / bands that are noticeably distinct from each other. Physically it is an even continuum of wavelengths, but look at it with your own eyes and you will see clear banding. This is due to way retina information is filtered to produce color signals before being fed into the brain. Why seven colors? Because Isaac Newton felt it must be 7 due to it being a more mystical number, so he shoved indigo in there.
  - itishappy 2y ago
    > Newton, who admitted his eyes were not very critical in distinguishing colours, originally (1672) divided the spectrum into five main colours: red, yellow, green, blue and violet. Later he included orange and indigo, giving seven main colours by analogy to the number of notes in a musical scale. > The question of whether everyone sees seven colours in a rainbow is related to the idea of linguistic relativity. Suggestions have been made that there is universality in the way that a rainbow is perceived. However, more recent research suggests that the number of distinct colours observed and what these are called depend on the language that one uses, with people whose language has fewer colour words seeing fewer discrete colour bands. https://en.wikipedia.org/wiki/Rainbow https://en.wikipedia.org/wiki/Rainbow

itishappy 2y ago

We have a discrete set of cones but they have continuous outputs so the space is indeed a continuum. The 6 colors of the rainbow are arbitrary and cultural (I've always learned there are 7). There's no physiological reason we say orange is a color but dark orange isn't. We perceive more than 7 colors.

adastra22 2y ago
The rainbow as perceived by most humans has six distinct color peaks / bands that are noticeably distinct from each other. Physically it is an even continuum of wavelengths, but look at it with your own eyes and you will see clear banding. This is due to way retina information is filtered to produce color signals before being fed into the brain. Why seven colors? Because Isaac Newton felt it must be 7 due to it being a more mystical number, so he shoved indigo in there.
- itishappy 2y ago
  > Newton, who admitted his eyes were not very critical in distinguishing colours, originally (1672) divided the spectrum into five main colours: red, yellow, green, blue and violet. Later he included orange and indigo, giving seven main colours by analogy to the number of notes in a musical scale. > The question of whether everyone sees seven colours in a rainbow is related to the idea of linguistic relativity. Suggestions have been made that there is universality in the way that a rainbow is perceived. However, more recent research suggests that the number of distinct colours observed and what these are called depend on the language that one uses, with people whose language has fewer colour words seeing fewer discrete colour bands. https://en.wikipedia.org/wiki/Rainbow https://en.wikipedia.org/wiki/Rainbow